An insurance customer installs two BladeCenter chassis in a rack with glass doors. After a short time, the blowers in both BladeCenters increase to full speed, and then one fails. Apart from replacing the broken blower, which additional action is required for a long term fix? （）

A.Add Rear Door Heat eXchanger 
B.Add fans to the top of the racks 
C.Increase circulation from Data Center raised floor 
D.Change to perforated doors